- Theoretically, any gas giant could be enclosed in a solid shell; at a certain radius the surface gravity would be terrestrial, and energy could be provided by tapping the thermal energy of the planet.
A more realistic plan, which, at least theoretically, would be possible in a more close future, is to react carbon with the abundant hydrogen, to form methane; a powerful greenhouse gas. If sufficient amounts of methane are formed, and the temperature is rased to −33.34 °C, ammonia-ice clouds would evaporate, contributing to the global warming. However, methane is mostly carbon by mass, thus the only way to create sufficient amount of methane, is to either bring an enourmous supply of carbon, or to create carbon by nuclear fusion. Both of which, are beyond our current technology.
Oxygen would also have to be brought/created in great emounts to react with hydrogen in the atmosphere
Because of the sheer size of the planet, constructing artificial continents is very impractical. Floating bases would be constructed for humans to live there. That presents another problem; Saturnian atmosphere is 96% hydrogen, the lightest gas, and the rest being helium; the second lightest gas, which makes it problematic to hold the base in the air. There are three ways to go around the problem:
-Use a hot air balloon instead.
-Use a solid shell, that would contain less dense air.
-Building an enomous balloon, filled with pure hydrogen, to compensate for helium in the atmosphere.